The first thing to do is back up everything in you bitcoin data directory. Backup the backups.

Ensure you are running the mainline bitcoin client .23 or .24.

First try the bitcoin -rescan option to rescan the block chain for transactions. See if this resolves your problems.

Secondly, your data directory may have corrupted blockchain or other files, the easiest way to rectify this is to remove all files except the wallet.dat, and download a nightly version of the the blockchain from http://eu1.bitcoincharts.com/blockchain/ and place this in the bitcoin data directory and launch bitcoin again and let it update to the latest block. If that doesn't fix your problem, try the -rescan option with this new blockchain.

If that fails, your wallet.dat is probably corrupted, restore from a recent backup, or use repair utilities on it.

The first thing to do is back up everything in you bitcoin data directory. Backup the backups.

Ensure you are running the mainline bitcoin client .23 or .24.

First try the bitcoin -rescan option to rescan the block chain for transactions. See if this resolves your problems.

Secondly, your data directory may have corrupted blockchain or other files, the easiest way to rectify this is to remove all files except the wallet.dat, and download a nightly version of the the blockchain from http://bitcoin.bluematt.me/bitcoin-nightly/blockchain-nightly/ and place this in the bitcoin data directory and launch bitcoin again and let it update to the latest block. If that doesn't fix your problem, try the -rescan option with this new blockchain.

If that fails, your wallet.dat is probably corrupted, restore from a recent backup, or use repair utilities on it.

Hey, i need to save this directory :C:\Program Files\Bitcoin?

Also i use bitcoin in a virtualbox, it's a problem ? And i use a VPN service, it's a problem also ?

Using bitcoin on a virtual machine is not a problem, it just adds one more layer of things that can break, like the day you can't mount your virtual hard drive.

The data directory is %APPDATA%\bitcoin, typically C:\Users\username\AppData\Roaming\Bitcoin. If you don't know where this is, you probably haven't backed up your wallet, which should be the first order of business - copy the wallet.dat file there to a USB stick and store it away, or 7-zip it with a strong password and email it to yourself, etc.

If the rescan option didn't work, then we next must suspect a corrupted blockchain database in the local client. Before starting copy the entire data directory to a new location, name the folder bitcoin-backup20110804 or such, so you can always put things back as they were if you screw it up.

You can then remove all the files in the data directory and the 'database' subdirectory except the wallet.dat. If you were to re-launch bitcoin now it will have to download the entire blockchain off the p2p network again, which can take many hours. To give it a head start, you can unzip the files from the bitcoin_blockchain_120000.zip file at http://sourceforge.net/projects/bitcoin/files/Bitcoin/blockchain/ into the bitcoin data directory. This download includes the blockchain up to April 2011, but still will require a normal p2p download and rescan of blocks 120000-139580, which is probably where your missing transactions are.

If after removing all old blockchain and database files the bitcoin client and letting the bitcoin client bootstrap from the network again, you are still getting an error about missing transactions and versions (and you've re-installed the client), then the wallet.dat is the only thing left that could be giving you problems. Were you ever running a different or forked version of bitcoin? Perhaps running that old client software will make it work correctly and you can get the bitcoins out. If you do not have a wallet.dat backup, then the only way to proceed after that is to look at corrupted wallet repairs.

I am using the 0.72 version, and I need days to update the blockchain file. Now, I met the same problem as OP met.

I am using Ubuntu10.04, in a VM6.0 environment.

The repair instructions are similar as posted above. The blockchain download is likely stuck or corrupted.

The bitcoin data directory is located at ~/.bitcoin (in your home directory). To repair, you will need to close Bitcoin, rename the files BLKINDEX.DAT, BLK0001.DAT, BLK0002.DAT, BLK0003.DAT, rename the "database" directory, and start Bitcoin again to re-attempt synchronization from the beginning, which may take many hours.